The Guardian has introduced a tool called Secure Messaging to protect journalistic sources, utilizing an open-source technology named CoverDrop. This system allows whistleblowers to communicate securely and anonymously with journalists by concealing the fact that messaging is occurring. CoverDrop integrates a module within The Guardian's mobile app, an untrusted cloud-based API, on-premises services known as CoverNode, and a desktop application for journalists. The CoverNode functions as a mix node to ensure the anonymity of sources. The app exchanges encrypted messages that appear indistinguishable from regular app data, providing cover for users. The technology has been rolled out to millions of users this year, and a white paper detailing its design has been published. Currently, the platform does not allow sharing of photographs or documents, but future plans include linking uploaded files with conversations. The source code for CoverDrop is available on GitHub under the Apache License 2.0.